A fabrication method for artificial small-diameter vascular grafts with multi-layer walls: stepwise lyophilization

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Polymer Science

Background:

• Artificial small-diameter vascular grafts (sdVGs) are needed to replace damaged vessels.
• Current sdVGs face challenges like poor wall structure and mechanical incompatibility.
• Precise control over graft architecture is crucial for clinical success.

Purpose of the Study:

• To develop a method for fabricating multi-layer sdVGs with controlled architecture.
• To investigate the impact of fabrication parameters on sdVG properties.
• To create biomimetic and biosafe artificial vascular grafts.

Main Methods:

• Fabrication of multi-layer sdVGs using biodegradable PU1 and biostable PU2 via modular mold-assisted stepwise lyophilization.
• Systematic variation of polymer solution solid content, mixed solvent ratios, and freezing temperatures.
• Characterization of sdVG microstructure, mechanical properties (strength), and cytotoxicity.

Main Results:

• Stepwise lyophilization enabled precise control over sdVG dimensions and layer configuration.
• Increased polymer solid content reduced porosity and pore size, enhancing mechanical strength.
• Freezing temperature influenced porosity and pore size, with mechanical performance showing complex correlations.
• Solvent composition affected pore architecture and mechanical properties, with polarity potentially causing delamination.

Conclusions:

• Modular mold-assisted stepwise lyophilization is a versatile technique for fabricating customizable sdVGs.
• The method allows for tuning structural, mechanical, and biological properties.
• This approach provides a framework for developing advanced, biomimetic, and biosafe vascular grafts.